1. Field of the Invention
The present invention relates to an adhesive chuck, and an apparatus and method for assembling substrates using the same, and more particularly to an apparatus and method for assembling substrates using an adhesive chuck that adheres to a substrate via an intermolecular attractive force.
2. Description of the Related Art
A substrate assembling apparatus is used for assembling liquid crystal display panels of liquid crystal displays (LCDs). One example of the LCD panels is a TFT-LCD panel. The TFT-LCD panel includes an array substrate having a plurality of thin film transistors (TFT) arranged in a matrix fashion, a color filter substrate having a color filter, a light shielding film, etc. and assembled to the array substrate while facing the array substrate with a gap of several micrometers formed therebetween, and liquid crystals injected into the gap before, during or after assembling the substrates and sealed to fabricate the panel.
Assembly of the substrates can be achieved by compressing the array substrate and the color filter substrate to each other. For this purpose, the apparatus is provided at upper and lower sides with two opposite electrostatic chucks to which the substrates are adsorbed, respectively. Then, with parallelism between the chucks maintained precisely, the chucks are moved toward each other, followed by assembling the substrates.
Most of such substrate assembling apparatuses is configured to perform a substrate assembling process in a vacuum atmosphere. At an initial stage of conveying the substrates into the apparatus, however, since the interior of the apparatus is at ambient pressure, a vacuum adsorption unit is used to adsorb the substrates, and when the interior of the apparatus becomes a vacuum state, the electrostatic chucks are used to adsorb the substrates. Examples of such a substrate assembling apparatus are disclosed in PCT WO 2004/097509, entitled “System for producing pasted substrate,” of Fujitsu Limited, PCT WO 2003/091970, entitled “Apparatus for assembling flat panel substrates,” of Shinetsu Engineering Kabushiki Kaisha, and the like.
Here, the aforementioned electrostatic chuck used for the assembling apparatus is the most typical one used to hold the substrate in a process of manufacturing semiconductors or display panels. One example of such an electrostatic chuck and a prior technique of assembling substrates using this chuck is disclosed in PCT WO 2004/084298, entitled “Substrate supporting mechanism using electrostatic chuck and method of manufacturing the same,” of Tokyo Electron Limited.
The electrostatic chuck is generally formed of an alumina sintered material or an alumina sprayed ceramic material, and includes electrode plates connected to a DC power supply to generate an electrostatic force via application of high voltage to the electrode plates from the DC power supply when supporting the substrate.
Such a conventional electrostatic chuck has several problems. Particularly, it suffers from large power consumption related to requirement of constant supply of DC power to the electrostatic chuck to hold the substrate, generation of spots on an LCD panel due to remaining static electricity associated with an electrode pattern in the chuck when the substrate is adsorbed to the chuck by the electrostatic force, and instability caused by accumulation of the electrostatic force.
Further, since the electrostatic chuck has a precise mechanical and electrical arrangement, it requires high manufacturing costs. Moreover, for an electrostatic chuck coated with a polyimide film, there is likelihood of damage to the polyimide film on the surface of the electrostatic chuck by broken particles of the substrate that can be generated during the process.